In recent years, plug-in hybrid electric vehicles (hereinafter, referred to as PHEVs) and electric vehicles (hereinafter, referred to as EVs) have been popularized. Such a PHEV or EV includes an in-vehicle charger that converts AC power supplied from outside into a direct current and outputs the direct current to a storage battery of the vehicle. The in-vehicle charger includes a reactor apparatus having a coil for an improvement in a power factor or smoothing.
A very high voltage of approximately 400 V is applied to the reactor apparatus used for an in-vehicle charger of the PHEV or EV. For this reason, the temperature of the coil becomes very high due to heat generation. In this case, in order to prevent overheating of the coil in the in-vehicle charger, it is important to provide a reactor apparatus having very high heat radiation properties. Additionally, it is also important to provide reliable electric insulation properties between the coil and a housing member for the coil.
As to a reactor apparatus including a coil, a technique disclosed in Patent Literature (hereinafter, abbreviated as PTL) 1 is known. The reactor apparatus disclosed in PTL 1 will be described below with reference to FIG. 1.
Bracket 12 surrounding transformer core 14 placed in heat sink 13 includes holding section 12a formed so as to be in close contact with transformer core 14, and heat transfer sections 12b extended from both ends of holding section 12a toward heat sink 13. The lower end (fixing section 12c) of each heat transfer section 12b is fixed to heat sink 13 with bolt B1. In heat sink 13, attachment hole 23 is formed at the position where transformer core 14 is disposed, and transformer core placement base 25 is provided at attachment hole 23. Then, transformer core 14 is fixed to heat sink 13 while being held between transformer core placement base 25, which is biased by compression coil spring 28 toward bracket 12, and holding section 12a of bracket 12.
According to the above-described configuration of the reactor apparatus disclosed in PTL 1, transformer core 14 even having non-uniform outside dimensions can be fixed to heat sink 13 while causing holding section 12a to be in close contact with top core 14a. Therefore, the heat generated from transformer 11 can readily be released to heat sink 13 through bracket 12.
Another reactor apparatus using resin having high thermal conductivity for enhancing heat radiation properties is disclosed in PTL 2. The reactor apparatus disclosed in PTL 2 will be described below with reference to FIG. 2.
The reactor apparatus includes base 1, core 2, coil 3, and fixing members 4A and 4B. Both ends 2A and 2B of core 2 are mounted on holding sections 1A and 1B of base 1, pressing surface 41A of fixing member 4A presses end 2A of core 2 against holding section 1A, and pressing surface 41B of fixing member 4B presses end 2B of core 2 against holding section 1B. Base 1, core 2, coil 3, and fixing members 4A and 4B are integrally molded using an unsaturated polyester resin having high thermal conductivity.
According to the above-described configuration of the reactor apparatus disclosed in PTL 2, heat generated in core 2 can be efficiently radiated to base 1 through holding sections 1A and 1B and the resin.